A new tetranuclear copper(II) Schiff base complex containing Cu4O4 cubane core: Structural and spectral characterizations

A new tetra-nuclear coordination complex [Cu4(HL)4] (1) containing Cu4O4 cubane core has been synthesized by using Schiff base ligand [(OH)C6H4CHNC(CH3)(CH2OH)2] (H3L), obtained by the 1:1 condensation of 2-amino-2-methyl-1,3-propanediol with salicylaldehyde and thoroughly characterized by micro-analytical, FT-IR, UV-Vis, thermal and room temperature magnetic susceptibility measurements. Structural characterization of the complex has been done by single crystal X-ray diffraction analysis. Structural elucidation reveals versatile coordination modes for two identical alkoxo oxygen atoms of the Schiff base ligand; one in its deprotonated form exhibits μ3-bridging to bind three similar copper(II) centers whilst the protonated one remains as monodentate or non-coordinating. Structural analysis also shows that the Cu4O4 cubane core in 1 consists of four μ3-alkoxo oxygen bridged copper(II) atoms giving an approximately cubic array of alternating oxygen atoms and copper(II) atoms where the metal centers display both distorted square pyramidal and distorted octahedral geometries.